C. Zhang, J. Zhang, L. Tang, Z. Mao, R. Zhu, and H. Zhang, “Effect of Acetic Acid and Propanoic Acid on Ethanol Fermentation by Saccharomyces cerevisiae in an Ethanol-Methane Coupled Fermentation Process”, ajc, vol. 23, no. 10, pp. 4701–4704, Aug. 2011.